yep it is practically normal.
There are days where you lo may need that sleep as there earlier naps may be short so they may have it. is this the 45min catnap you are talking about?
i always dred putting my little one down at 5pm and not knowing if she is going to take it or not, but sometimes she surprises me. Just perservier with it, as others have said it only gets easier
But also normally at this time they are normally more tired, so maybe try low key activities, go for a walk, not too much stimulation. And sometimes just leaving them alone is enough even if you put them outside to look at the trees etc is enough activity.
kirsten